Projectile with a bourrelet retaining a segmented ring in a core-groove



Aug. 23, 1955 c. E. HABLUTZEL EIAL 2,

PRO TILE WITH A BOURRELET RETAINING A GMENTED G IN A CORE-GROOVE Filed ug. 2, 1945 INVENTORS /9 MARLES E. HABLUTZEL WILL/AME ELY BY :5 5 0&4

ATTORNEY PROIECTILE WITH A BOURRELET RETAINING A SEGMENTED RING IN A CORE-GROOVE Charles E. Hablutzel and William F. Ely, Albuquerque, N. Mex., assignors to the United States of America as represented by the Secretary of the Navy Application August 2, 1945, Serial No. 608,597

1 Claim. (Cl. 102--'93) This invention relates to projectiles for guns and, particularly, to sabot-type projectiles in which a discardable sabot and bourrelet are released axially, thus permitting the projectile to be fired safely through a muzzle brake.

In projectiles having a sub-caliber core and releasable sabot, a difficulty frequently encountered is that of holding the component parts of the projectiles together prior to loading into the gun, without impairing proper release of the sabot after firing. This difliculty was to a degree dealt with in some cases by assembling the projectile parts somewhat loosely. In such projectiles, however, considerable trouble is sometimes entailed in handling, as in packing operations at the factory, or while unpacking or loading in the field. Unless particular care is observed, the component elements frequently separate,

in which event it is easily possible that some of the elements will be lost of damaged. At best, considerable time must be consumed in re-assembling the separated elements, and in service use this is a serious disadvantage. Even Where provision is made for positive retention of the projectile parts, a further problem arises in obtaining release of the sabot early in its flight after firing.

Accordingly, an object of the invention is to provide a projectile in which a sub-caliber core and a sabot are locked in assembled relationship, the sabot being releasable after the projectile is fired without deflecting the core from its initial direction of flight, but being firmly held on the core prior to firing.

Another object of the invention is the provision of a projectile in which a sub-caliber core and a sabot are positively held in assembled relationship in such a manner as to overcome the above described difiiculties, and are separable either in the barrel under acceleration, or after the projectile has commenced its flight through the action of wind resistance acting on the discardable parts.

A further object of the invention is to provide a projectile of the character referred to above which is simple to manufacture and is adapted to large quantity production.

Other and ancillary objects and advantages of the invention will be apparent from the following specification and the acompanying drawing in which:

Fig. 1 is a side elevational view, partly in section, of a preferred form of the invention;

Fig. 2 is a cross-sectional view taken along line 22 of Fig. 1;

Fig. 3 is a longitudinal sectional view of the rotating band for the sabot used with the projectiles of our invention;

Fig. 4 is a side elevational view, partly in section, of a modified form of the projectiles contemplated by our invention;

Fig. 5 is a cross-sectional view taken along line 55 of Fig. 4.

The projectile assembly in the form illustrated, particularly in Figs. 1 and 4, includes a sub-caliber core 11 with substantially parallel sides 12, an ogive nose portion 13, and an axially extending rear hub or fuze plug 14 of reduced diameter which may be integral with the core or suitably attached thereto. An elongated cylindrical bourrelet 16 is fitted over the core 11 and is secured at its forward end to the core by a plurality of shear pins 17. The pins, of course, may be of any design well known in the art, and may be either smooth or threaded; we prefer to use threaded shear pins for this purpose. A sabot 18 is loosely fitted over the hub 14, and is secured to the rearward endof the bourrelet 16 by any convenient means, such as threads 19. A rotating band 20 of copper or other suitable material is mounted by press fitting or other suitable means in the annular grooves 21 on .the periphery of the sabot.

In order to assure complete separation of the discardable parts from the core of the projectile after only a minimum of relative movement therebetween, we preferably separate the bourrelet from the core by a narrow annular space 22. A shoulder 23 formed by a slight increase in the diameter of the core at the base of the ogive portion and an annular ring 24 integral with the forward face of the sabot 18 serve to effect this separation. Thus, it can be seen that only a small rearward movement of the bourrelet and sabot will be required to bring about a complete separation of the discardable exterior parts from the sub-caliber core 11. A ring 26 of steel or the like is fixed, as by threads (undesignated), on the forward end of the bourrelet 16 and acts as a front bearing surface between the bourrelet and the gun bore. The sabot 18 may abut the rearward face of core 11 or a narrow annular space, such as 27, may be provided between these parts.

In the sub-caliber projectile depicted in Fig. 4 most of the components are substantially the same as their counterparts shown in Fig. 1. However, in this modification the annular space 22 is defined by a forward bourrelet spacer ring 28 of steel or the like and by an annular rearward shoulder 27 integral with the bourrelet structure. The ring 28 is preferably segmented as shown in cross-section in Fig. 5, and is loosely assembled in a shallow groove 29 in the core 11 from which it is free to fly under centrifugal force after the bourrelet 16 has moved axially rearwardly a very short distance.

When the projectile illustrated in Fig. 1 is fired from a gun the force of explosion of the propellent charge causes the sabot-bourrelet assembly to move forward on the core 11, severing the shear pins 17 at the interface between the relatively movable parts, thus bringing the forward face of sabot 18 into high-pressure contact with the rearward face of core 11. This contact is maintained throughout the interval of acceleration in the gun bore of the projectile assembly and is the means by which the rotation imparted to the sabot by the rifling of the gun bore is transmitted to the sub-caliber core 11. The extent to which the sabot rotation is transmitted to the core is dependent, of course, upon the condition of smoothness or roughness of the contacting surfaces, and it is within the contemplation of the present invention so to condition these surfaces, as by knurling or serrating, that the substantially complete transmission of such rotation is assured. Proper axial alignment of the entire projectile assembly within the gun barrel is maintained by contact of the bearing ring 26 with the lands of the rifle bore. Upon emerging from the gun barrel, the core is immediately swept of the discardable parts, i. e., the sabot and bourrelet, by wind resistance, permitting the core to continue its normal flight.

The manner of separation followed by the modification depicted in Fig. 4 is somewhat different. Upon firing, the sabot rotation is transmitted to the core in the same maner as that described above. However, since this design does not permit of any relative movement between the component parts while in the gun barrel, the

projectile commences its air travel intact and as a unitary assembly. Immediately thereafter, air pressure acting upon the forward bourrelet surface causes the sabotbourrelet assembly to move axially rearwardly on the core 11, thereby severing shear pin 17. The bourrelet spacer ring 28 is shed tangentially under centrifugal force as soon as it is no longer confined by the bourrelet.

While what has been described is particularly illustrative of a presently preferred embodiment of my invention, it is not intended that the scope of the invention be limited thereto but that it embrace any modificaions and changes which fall within the true spirit of the invention, as covered by the appended claim, accurring to those skilled in the art.

We claim:

In a gun-fired projectile having an ogival sub-caliber core, a segmented spacer ring, said core having an annular groove at the aproximate base of the ogive thereof, occupied by the ring and defining front and back shoulders limiting the axial displacement of the sections of 20 internal annular shoulder at its rear end engaging the 1 core, a shear pin driven through the bourrelet and shoulder into the core to maintain the bourrelet and spacer ring assembly until the projectile is fired, and a sabot mounted on the bourrelet at said rear end, furnishing rear end projectile support.

References Cited in the file of this patent UNITED STATES PATENTS 41,127 Smith Jan. 5, 1864 FOREIGN PATENTS 46,057 Sweden Nov. 5, 1919 812,680 France Feb. 8, 1937 

